A number of radioactively labeled compounds are being studied for possible utility in imaging healthy or damaged myocardium. Fluorine-18 fluorodeoxyglucose is being evaluated in humans and the uptake in myocardium correlated with blood levels of glucose and lipids. Ruthenium-97 compounds for muscle localization and bone imaging are being developed and studied in animal models. Potassium-38 is being used to assess the effects of intervention after experimental infarction in dogs. Manganese-51 and manganese-52m will be evaluated for myocardial imaging.